New half sister advice please

[Starryargenta]

I've just discovered that my 5 yr old son has an 8 month old half sister. I am divorced from the father but have regular contact with him.
The half-sister was the result of a brief affair and he says he has only just told me as he was waiting for the results of a paternity test.
I am confused as to what sort of relationship my son should have with her. Has anyone had a similar experience?

That is a bit of a shock for you. I guess it really depends on the kind of relationship your ex is going to have with her. If he is going to have regular contact then I think it'd be good for them to have as normal a sibiling relationship as possible (when no shared residency is in place).

Perhaps you could suggest to your ex that he has both children together on the same weekends?